A radical forward-swept-wing design with great performance
Trishula is ancient Sanskrit for “trident,” and after you see this model in flight, you’ll understand why I gave it its name: The model looks like a flying pitchfork. I wanted this one to be really different. The model has 32-degree forward-swept wings (FSW) and retracts. With this odd planform, the retract geometry proved to be challenging, yet it seems to work just fine.
The Trishula actually performs very well. My flying buddy, Keith Shaw, flew it at the Mid-America Electric Flies and was quite pleased with its performance.
Why use a FSW setup? Well, it’s different, and the wing has excellent stall characteristics and increased maneuverability.
The drawbacks are the requirement for a very stiff wing to avoid aeroelastic diversion, better known as “wing twist.” Because of this, I used a fully sheeted foam wing for increased torsional rigidity.
This is not a beginner’s model in any sense. It uses some advanced construction techniques and must be built precisely to fly well. Any unevenness in the wings or misalignment can—and
will—result in an almost uncontrollable model. It must be built correctly. So I’ll assume anyone building the Trishula will have significant building experience, and I’ll provide just a basic overview of the construction.
BUILDING THE WING
I used pink foam for the cores, and the templates are shown on the plans. Cut them accurately with no washout (or wash-in). Using the templates, cut the dihedral 10 degrees per panel (yes, 20 degrees total). Remember to do this before cutting the core planform or the angle will not be correct. Also note the wheel wells need to be cut at odd angles to allow the wheels to “slip” rearward into the wells. Cut out the portion
of the wing where your retract or landing-gear mount blocks will be installed, and build up the mounts from hardwood and aircraft plywood using the templates on the plans. Install the bearers in the wing before sheeting the wing with 1/16-inch balsa. Also install the tubes in the wings for the aileron servo leads and retract wires. After sheeting the wings, install the
Trishula | X0518A Designed by Mark Rittinger, the Trishula is a radical-looking, forward-swept-wing design that has great performance. It is not a beginner plane to build or fly. Using foam-core wings, the design has retracts and uses traditional modelairplane construction. Be sure to keep everything square and properly aligned and you’ll have an amazing highperformance airplane. WS: 51 in.; L: 56 in.; Radio: 4-channel; Power: E-flite Power 32; LD: 3; 1 sheet; $16.95
trailing edge and then join the panels with the center rib, and use a nylon or fiberglass glasscloth center wrap to reinforce the glue joint.
BUILDING THE FUSELAGE
The fuselage is basic balsa and plywood and must be built straight and true. Build up the left and right sides using sheeting and square stock, then assemble the battery tray/bulkhead. Leave off the bottom front block until you fit the wing in place so that you can drill the alignment-dowel hole. The wing must be set at 0 degrees in the saddle. Again, ensure that it’s all straight and the wing and stabilizer are at the correct incidences as shown on the plans. The prototype required some downtrim, so I corrected for this on the plans. I strip-planked my rear deck, but sheeting will also work.
Note that the right- and down-motor thrust is built into the fuselage; these are important. Because the center of gravity (CG) is actually forward of the wing root, I also used brass grommets in the fuselage at the CG location to help with balancing. Just slide a length of music wire through them, and add ballast as needed.
BUILDING THE TAIL
Sheet balsa is used for the vertical and horizontal stabilizers. The fin and rudder are a simple affair, while the horizontal stabilizer needs to be built with an outline of hard balsa square stock to help keep it from twisting during flight. The center joint must be strong as well. Be sure to attach the horizontal stabilizer at 1/2-degree positive incidence.
Assemble the model after covering, again making sure that it’s 100 percent in line and straight. Study the plans for incidental info such as tailwheel, wing mount, fillets, pushrods, gear doors, and gear mounting.
Balance with the landing gear in the up position, as it folds rearward on retraction and will move the CG rearward as well. My prototype
The Trishula has a unique appearance while flying. The forwardswept-wing planform takes a little getting used to.
This shot of the model, just as it is starting its landing flare, shows how unusual it looks with its forward-swept-wing arrangement.
The basic fuselage structure is being assembled and placed on the wing assembly.
This shows the tail surfaces and fairing block installed and shaped to blend into the turtle deck.
Here, you see the alignment dowel in place in the center joint of the wing assembly.
It’s starting to look like a complete airplane. The fuselage sides have been joined at the tail, the turtle-deck sheeting has been applied, and the nose blocks have been installed and shaped.